Three decades of work by neuroscientists have established that a physiological effect known as long-term potentiation (LTP) encodes everyday forms of memory. In the Journal of Neuroscience today, a UC Irvine research team led by neuroscientists Christine M. Gall and Gary Lynch presents these unique images, which show that the size and shape of synapses that were changed by LTP.
“The way is now open to mapping where in the brain memories are laid down,” said Lynch, a professor of psychiatry and human behavior. “Seeing memory-related physical changes to synapses means that we can at last use mouse models to test if the effects of retardation, aging and various cognitive disorders involve a specific, long-suspected defect in the connections between cortical neurons.”
Brain tissue collected from rats and mice was kept alive in specially constructed equipment. The researchers induced LTP by stimulating synapses with a rhythm known to be critical to memory formation. The brain slices were then sectioned and stained with one antibody that attaches to activated proteins involved with LTP and a second one that labels synapses. Newly developed microscopic methods were used to visualize and measure synapses that had both antibodies attached.
In addition to revealing new information about the formation of memory in the brain, this study and another published last month in the Journal of Neuroscience by the UC Irvine researchers have shown how LTP deficiencies accompany the memory loss seen during the early stages of Huntington’s disease, an incurable neurodegenerative disease characterized by disturbances to memory and learning.
Lynch, Gall and colleagues found that LTP structures encoding memory are defective in mouse models of Huntington’s disease. They discovered that these synaptic defects can be fully reversed through treatment with a brain growth factor released at synapses. Ampakines, a new class of drugs developed by Lynch at UC Irvine that are currently in clinical development for Alzheimer’s disease and ADHD, increase the levels of this growth factor and potentially emerge as therapy for the cognitive problems associated with Huntington’s.
The researchers are now working to see if such LTP defects are present in mouse models of common forms of human mental retardation.
Source: University of California - Irvine
Related stories:
Astrocytes and synaptic plasticity
By mopping up excess neurotrophic factor from neuronal synapses, astrocytes may finely tune synaptic transmission to affect processes such as learning and memory, say Bergami et al.
Cocaine addiction linked to voluntary drug use and cellular memory
Rats that voluntarily use cocaine show a persistent cellular memory in the brain's reward center even after several months of abstinence from the drug, while their involuntary counterparts had no such memory, according to a new study by researchers at the University of California, San Francisco.
Brain's reaction to self-administered cocaine differs
New research has uncovered a fundamental cellular mechanism that may drive pathological drug-seeking behavior. The study, published by Cell Press in the July 31 issue of the journal
Neuron, examines the brain's reward circuitry and details strikingly distinct influences of self-administered cocaine compared to natural rewards or passive cocaine injection.
Researchers restore memory process in most common form of mental disability
University of California, Irvine scientists have discovered how to reverse the learning and memory problems inherent in the most common form of mental impairment.
How emotionally charged events leave their mark on memory
Researchers have uncovered new evidence in mice that may explain how emotionally charged situations can leave such a powerful mark on our memories. Surges of the stress hormone norepinephrine (also known as noradrenaline) that often accompany strong emotions spark a series of molecular events that ultimately strengthen the connections between neurons, the team reports in the October 5, 2007, issue of the journal
Cell.
Scientists unveil the 'face' of a new memory
A century-old dream of neuroscientists to visualize a memory has been fulfilled, as University of California, Irvine researchers, using newly developing microscopic techniques, have captured first-time images of the changes in brain cell connections following a common form of learning.
Research sheds light on memory by erasing it
For years, scientists have studied the molecular basis of memory storage, trying to find the molecules that store memory, just as DNA stores genetic memory. In an important study published this week in the Journal of Neuroscience, Brandeis University researchers report for the first time that memory storage can be induced and then biochemically erased in slices of rat hippocampus by manipulating a so-called "memory molecule," a protein kinase known as CaMKII.
Morphine makes lasting -- and surprising -- change in the brain
Morphine, as little as a single dose, blocks the brain’s ability to strengthen connections at inhibitory synapses, according to new Brown University research published in
Nature.
